Synchronous data characterizing, for example, voice or video signals, is typically transmitted from a source to a receiver via a particular type of connection commonly referred to as a circuit switched connection. Typically, a circuit switched connection is a dedicated connection between the source and receiver. The reason for requiring a circuit switched connection for the transmission of synchronous data is to ensure that the data is delivered to the receiver at an expected rate. If the circuit switched connection imposes a delay in the delivery of the data, then the delay needs to be a constant fixed amount of time between each transmission of the data. In the ideal situation the fixed delay would be very close to zero seconds.
In contrast to the circuit switched connection is the so-called packet switched connection. A packet switched connection is typically used to transmit data that is not time sensitive, such as asynchronous data. If a packet switch were used to transmit synchronous data, then it is likely that the constant fixed delay that is needed between each transmission of such data packets could not be met. In such a situation, a packet receiver which fails to receive an expected synchronous data packet may supply to an intended destination a random value, such as a null word, for the expected synchronous data. In such an instance the random value could cause the intended destination to perform an unintended function. For example, if the intended destination is a telephone station set, then the station set might decode the random value into a signal characterizing either a "clik" or "pop". As a further example, if the intended destination is a video receiver, then the video receiver could decode the random value into an incorrect video image.